Calculate RFC482 (SLAAC) IPv6 address a host will obtain

ip6-eui64-address.py

#!/usr/bin/env python3
#
# Calculate the IPv6 address a host will obtain per RFC4862
#
# Usage: ./ip6-eui64-address.py --prefix 2001:db8::/64 52:54:00:59:c2:b3
#
# Author: Wido den Hollander <wido@denhollander.io>
#
import argparse
import ipaddress
import re

def mac2eui64(mac, prefix=None):
    '''
    Convert a MAC address to a EUI64 address
    or, with prefix provided, a full IPv6 address
    '''
    # http://tools.ietf.org/html/rfc4291#section-2.5.1
    eui64 = re.sub(r'[.:-]', '', mac).lower()
    eui64 = eui64[0:6] + 'fffe' + eui64[6:]
    eui64 = hex(int(eui64[0:2], 16) ^ 2)[2:].zfill(2) + eui64[2:]

    if prefix is None:
        return ':'.join(re.findall(r'.{4}', eui64))
    else:
        try:
            net = ipaddress.ip_network(prefix, strict=False)
            euil = int('0x{0}'.format(eui64), 16)
            return str(net[euil])
        except:  # pylint: disable=bare-except
            return

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Calculate IPv6 address based on Prefix and MAC')
    parser.add_argument('mac', help='MAC address to be used')
    parser.add_argument('--prefix', help='IPv6 prefix', default='fe80::/10')
    args = parser.parse_args()

    prefix = ipaddress.ip_network(args.prefix)
    if prefix.version != 6:
        raise ValueError('Prefix should be IP version 6')

    if prefix.prefixlen > 64:
        raise ValueError('Prefix should be at least 64-bits in size')

    address = ipaddress.ip_address(mac2eui64(mac=args.mac, prefix=str(prefix)))
    print(address)